Leaving Porto Seguro, the boats (that work 24 hours), takes the tourists through Rio Buranhém (the crossing lasts from 10 to 15 minutes). You can also take the bus for the 4 km. it takes.
Use http://www.br.map24.com/ to find your way. "Endereco" means "address". "Rua" means street. "Cidade" means City". "Proxima" means next.